Electrical tree degradation in high‐voltage cable insulation: progress and challenges

Abstract

High‐voltage direct current (HVDC) and high‐voltage alternating current (HVAC) cables are the most important equipment for high‐voltage, large‐capacity and long‐distance power transmission. Electrical tree is a pre‐breakdown phenomenon leading to failure of insulation materials, and it is the major issue that threatens the safe and stable operation of HVDC and HVAC cable systems. This study summarises and analyses the achievements in the research of electrical tree for HVDC and HVAC cables. The initiation mechanisms of the electrical tree, including Maxwell electro‐mechanical stress, charge injection–extraction, charge trapping and electroluminescence theories, are elaborated for fully understanding the electrical degradation process in insulation materials. Then, the influences of the high electric field, high temperature and mechanical stress on electrical tree behaviours are discussed, and the relationship between charge transport and the electrical tree is analysed and illustrated. The suppression methods of the electrical tree are put forward by introducing inorganic and organic additives into insulation materials, and the suppression mechanisms are presented from the viewpoints of the structure‐property and microscale–macroscale relationships. Recently, the electrical tree research studies are focused on the high‐precision of initiation models, high‐dependence of multi‐physical fields and high‐efficiency of suppression methods. The achievements provide theoretical support for improving the electrical performance of insulation materials, while it is a practical problem to explore their application feasibility in HVDC and HVAC cable.

Simultaneously Enhanced Thermal Conductivity and Dielectric Breakdown Strength in Sandwich AlN/Epoxy Composites

“…Along with their rapid development within the electronic and electrical industry, high dielectric breakdown strength materials have attracted increasing attention due to their potential application in high-voltage equipment and power electronic devices with high power density (e.g., insulated gate bipolar transistor) [ 1 , 2 , 3 , 4 ]. Recently, polymer-based composites with high dielectric breakdown strength have been the focus of a large number of studies, due to their flexibility, low cost and processability [ 5 , 6 , 7 , 8 , 9 ].…”

Optimal Design of Functionally Graded Power Cable Joint Utilizing Silicone Rubber/Carbon Nanotube Composites

“…The vulnerability of cable accessories is strongly correlated to the nonuniform distribution of the internal electric field (E-field). This locally intensified E-field stress can lead to electrical treeing and partial discharge, further causing insulation failure [5,6].…”

“…Despite their effectiveness in Efield grading, a strong mismatch in permittivity or conductivity between the stress cone and insulation medium (regions A and B in Fig. 1) may become a new source of Efield intensification, especially when improper installations or residual impurities are considered [6]. Recently, functionally graded materials (FGMs) have become a promising solution for E-field regulation problems in electrical insulation systems.…”

Electrical Property of Polypropylene Films Subjected to Different Temperatures and DC Electric Fields

“…Polymeric materials are often used as insulation materials in cables in high-voltage applications. As one of the most widely used polyethylenes (PE) [3][4][5], the aging and electrical properties of cross-linked polyethylene (XLPE) are of great concern [6][7][8][9]. Compared to PE, PP has a relatively high melting temperature that might possibly facilitate higher current-carrying capacity in addition to other micro-structure properties, such as crystallinity, amorphous phase, as well as crystalline/amorphous interface [10].…”